JP2003297325A - Sealed battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery wherein cycle characteristics is enhanced without causing swelling of the battery, by making it possible to exhaust hydrogen gas generated in the battery to the outside of the battery. <P>SOLUTION: In this sealed nonaqueous electrolyte secondary battery, an exhaust part 20 is formed by providing an exhaust port 15e in a sealing material, and a hydrogen permselective alloy film 23 to selectively permeate hydrogen gas is provided in this exhaust part 20. If the hydrogen permselective alloy film 23 is provided in the exhaust part 20, hydrogen gas generated in the battery is exhausted to the outside of the battery through the hydrogen permselective alloy film 23. Thereby, even if the battery is left alone in high temperatures, swelling of the battery caused by the hydrogen gas is suppressed. In addition, since the hydrogen gas is not stored in the battery, hindrance to battery reaction caused by the hydrogen gas is reduced, and the nonaqueous electrolyte secondary battery having enhanced cycle characteristics can be obtained. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] TECHNICAL FIELD The present invention relates to a positive electrode, a negative electrode,
A separator that separates these positive and negative electrodes, and an electrolyte
Inside the outer can, and the opening of the outer can is sealed with a sealing body
And a sealed battery. [0002] 2. Description of the Related Art In recent years, small video cameras, mobile phones,
Used as a power source for portable electronic and communication devices such as laptop computers.
Therefore, compact, lightweight and high capacity sealed batteries are used.
Swelled. Such sealed batteries include lithium.
Uses graphite capable of occluding and releasing ions as negative electrode active material
Lithium-containing cobalt oxide (LiCoO_Two), Re
Manganese oxide containing lithium (LiMn_TwoO_Four), Etc.
Organic metal-containing transition metal oxide as the positive electrode active material.
Using an electrolyte in which a lithium salt is dissolved as a solute in a medium.
Non-aqueous electrolyte secondary batteries are often used.
Potassium storage batteries and lead storage batteries are also used. [0003] By the way, such a problem is solved.
In sealed batteries, the charge / discharge cycle was repeated
If left at high temperatures, gas is generated in the battery and
If power cycle characteristics deteriorate or battery swells
Problem. It has repeated charge and discharge cycles
Generated gas such as hydrogen gas or carbon dioxide gas
So that the accumulated gas stays between the plates
To act to inhibit the battery reaction.
You. On the other hand, sealed type batteries such as non-aqueous electrolyte secondary batteries are used.
If the pond is left at high temperatures, the electrolyte will be decomposed and hydrogen
A large amount of gas is generated. Because of this, battery swelling
Is presumed to have occurred. In particular, this problem of battery swelling
Is the thickness of the outer can to achieve high energy density
This is remarkable in a prismatic battery having a reduced thickness. And the battery
When swelling occurs, the battery case containing this battery
(A battery pack containing a protection circuit and multiple batteries
S) also swells and fits with the electronic equipment to which the battery case is attached
Causes problems such as deterioration of Therefore, the present invention solves the above problems.
It was made to erase and occurred in the battery
By allowing hydrogen gas to be discharged outside the battery, battery swelling
Sealed type with no cycle and improved cycle characteristics
The purpose is to provide a pond. [0006] Means for Solving the Problems To achieve the above object,
Therefore, the sealed battery of the present invention may be partially
Exhaust part that exhausts hydrogen gas generated inside the battery to a part of the body
Water that selectively permeates hydrogen gas into the exhaust
Characterized by having an elementally permeable alloy membrane
Things. Here, hydrogen that selectively permeates hydrogen gas
If a selectively permeable alloy membrane is provided in the exhaust,
Hydrogen gas generated in the pond passes through this hydrogen selective permeable alloy membrane.
Through the battery. This allows high
Battery swelling due to hydrogen gas can be suppressed even if the battery is left at a temperature
I will be able to. Also, do not allow hydrogen gas to accumulate in the battery.
To reduce the inhibition of battery reaction by hydrogen gas
Therefore, a sealed battery with improved cycle characteristics can be obtained.
Swell. In this case, the hydrogen selectively permeable alloy is combined with the electrolyte.
The substance melts upon contact, and the dissolved substance
Pond reactions may be adversely affected. For this reason, hydrogen selection
Gas permeable so that the selectively permeable alloy membrane does not come in contact with the electrolyte
Selective hydrogen permeation on a conductive thin film (permeation of electrolyte is blocked)
This gas permeable thin film is formed by forming a transient alloy film.
Should be arranged facing the inside of the battery. Further, such a hydrogen selective permeable alloy membrane is
This film is thin and has low strength.
When placed in a part that is isolated by
If it rises, it may be destroyed. For this reason, batteries
Provide space to relieve pressure between inside and outside of battery
And place a hydrogen selective permeable alloy membrane in this space
It is desirable to do so. [0010] Then, between the inside of the battery and the outside of the battery,
In order to provide a space to relieve pressure between
The electrode is placed on top of the gas permeable thin film on which the selectively permeable alloy film is formed.
If you place a membrane that separates the inside of the pond from the outside of the battery
Good. [0011] BRIEF DESCRIPTION OF THE DRAWINGS FIG.
The present invention will be described with reference to FIGS.
The present invention is not limited to any
It is possible to change and implement as appropriate within the range not present. What
FIG. 1 shows a rectangular non-aqueous electrolyte secondary battery having a spiral electrode body.
It is sectional drawing which shows schematic structure of a pond, FIG.1 (a) is BB.
It is a figure which shows a cross section, FIG.1 (b) is a figure which shows AA cross section.
It is. FIG. 2 shows an example in which an exhaust portion is provided in the sealing body of FIG.
Exhaust of Example 1 in which a hydrogen selective permeable alloy membrane is arranged in the section
It is sectional drawing which shows a part. FIG. 3 shows an exhaust unit according to the second embodiment.
It is sectional drawing. FIG. 4 is a cross-sectional view illustrating an exhaust unit according to the third embodiment.
is there. Figure 5 shows the storage time and internal pressure of a battery left at high temperature.
FIG. 6 and 7 are left at high temperature.
The relationship between the battery storage time or days and the battery expansion rate
FIG. 1. Fabrication of negative electrode First, the spacing (d) of the (002) plane₀₀₂) Is 0.336n
m, the crystallite size (Lc) in the c-axis direction is 200 nm
A lump graphite having an average particle size of 20 μm (fired at 2950 ° C.)
Of artificial graphite) was prepared. Then, this graphite powder
And styrene-butadiene rubber (SB) as a binder
R) (solid content 48% by mass) with water
Carboxymethyl cellulose as a thickener after dispersing
Anode slurry is prepared by adding and mixing
Was. In addition, the mass after drying of massive graphite, SBR, and CMC
The composition ratio is lump graphite: SBR: CMC = 95: 3: 2.
Was prepared as follows. Then, a negative electrode current collector made of copper foil is prepared.
Then, the negative electrode slurry prepared as described above is
100 g / m2 per unit area of the negative electrode current collector on both sides of the body
^TwoIs applied by a doctor blade method to form a negative electrode active material layer.
Was formed. Then, it was vacuum-dried at 100 ° C. for 2 hours.
Thereafter, the packing density of the graphite material is 1.6 g / cm.^ThreeTo be
To form a strip-shaped negative electrode plate 11
Made. The negative electrode plate 11 extends from one end of the negative electrode
An electric tab 11a is formed. 2. Preparation of positive electrode Lithium cobaltate having an average particle size of 5 μm (LiCoO_Two)
Powder and artificial graphite powder as a conductive agent in a mass ratio of 9: 1
The mixture was mixed at a ratio to prepare a positive electrode mixture. This positive electrode mixture,
N-methyl-2-pyrrolidone (NMP)
A binder solution in which 5% by mass of niliden (PVdF) is dissolved;
And kneaded so that the mass ratio of the solid content becomes 95: 5.
An electrode slurry was prepared. Next, a positive electrode current collector made of aluminum foil
A body was prepared, and the positive electrode slurry prepared as described above was
240 g per unit area of positive electrode current collector on both sides of current collector
/ M ^TwoIs applied by a doctor blade method,
A layer was formed. After that, vacuum drying at 150 ° C. for 2 hours
After that, the packing density of the positive electrode mixture is 3.2 g / cm^ThreeWill be
And cut into a predetermined shape to form a belt-shaped positive electrode plate 12.
Produced. In addition, in the positive electrode plate 12, the outermost
Do not apply the positive electrode slurry to the area
Cut and raise the minium foil to form a positive electrode lead (not shown)
Has formed. 3. Fabrication of non-aqueous electrolyte secondary battery Next, the negative electrode plate 11 and the positive electrode plate manufactured as described above were used.
And a microporous polyethylene membrane between them
Spiral with the separator 13 made of
It was wound in a shape. Then, press this so that it is flat
After forming a prismatic electrode group, the prismatic electrode
The group was inserted through the opening of the outer can 14. Next, the electrode group
After arranging the spacer 16 on the top of the negative electrode plate 1 of the electrode group
A negative electrode current collecting tab 11a extending from 1 is provided on the sealing body 15.
The terminal plate 15c was welded to the inner bottom. On the other hand, the electrode group
The positive electrode lead extending from the positive electrode plate 12 is sealed with the outer can 14.
Remove the sealing body 15 so that it is sandwiched between the
It was arranged at the opening of the can 14. Then, open the outer can 14
Laser welding was performed between the peripheral wall of the mouth and the sealing body 15. And ethylene carbonate (EC)
Mixed solvent consisting of methyl ethyl carbonate (MEC)
(EC: MEC = 30: 70: volume ratio) LiPF₆To
1 mol / liter was dissolved to prepare an organic electrolyte solution. this
The organic electrolyte prepared as described above is provided on each terminal plate 15c.
After pouring into the outer can 14 through the through hole,
The terminal 15a was welded to each terminal plate 15c and sealed. to this
More, the design capacity is 700 mAh and square (thickness: 5 mm,
Non-aqueous electrolyte secondary battery (width: 30 mm, height: 48 mm)
A was prepared. The sealing body 15 is not shown.
A safety valve is provided to generate gas in the battery and
When the gas rises, the generated gas is released outside the battery.
It has been done. 4. Production of exhaust part (1) Example 1 Here, as shown in FIG.
15e, and the upper annular groove 1 is formed in the peripheral wall of the exhaust port 15e.
5f and a lower annular groove 15g were provided. And this top
A resin sheet having gas permeability in the annular groove 15f (for example,
For example, a polyethylene (PE) sheet 21
We are trying to cut off from the outside. Also select hydrogen gas
Zirconium (Zr) and nickel (Ni)
Amorphous alloy (for example, 36Zr-
64Ni alloy) film 23 and the alloy film
Around the resin sheet 21 made of the same material as the resin sheet 21 described above.
To form a composite film. And this composite membrane
Was fixed to the lower annular groove 15g. In this case, the periphery of the alloy film 23 and the resin sheet
22 means by using appropriate means such as pressure bonding, heat welding, and adhesion.
What is necessary is just to fix it. Also, the upper annular groove 15f and
Fixing to the resin sheet 21 and duplication with the lower annular groove 15g
For fixing to the composite film, these films are connected to the respective annular grooves 15f and 15g.
After inserting into these, fill these parts with adhesive and glue them
do it. Thereby, the alloy film 23 and the resin sheet 22
A space is formed between the composite film made of
Pressure regulation to reduce the pressure difference between the inside and outside of the battery
The exhaust unit 20 having the regulating room 20a formed therein;
Become. Provision of such an air pressure adjusting chamber 20a
Thus, for example, even if the pressure inside the battery rises
Gradually through the composite film consisting of the gold film 23 and the resin sheet 22
Then, hydrogen gas flows into the pressure adjusting chamber 20a.
You. Due to this, the pressure inside the pressure adjusting chamber 20a rises rapidly.
Can be prevented, and the pressure in the pressure adjusting chamber 20a can be reduced.
When the specified value is reached, gas is released outside the battery.
You. This makes amorphous alloy film with low mechanical strength
23 can be prevented from being broken by a pressure difference.
You. The amorphous alloy film 23 is made of non-aqueous
Constructs this amorphous alloy when in contact with liquid
Nickel (Ni) elutes into the electrolyte and flows into the battery
As a result, the battery reaction may be adversely affected. But
However, in the present invention, the periphery of the amorphous alloy film 23 is
The surrounding is a composite film fixed to the resin sheet 22.
For this reason, this gas-permeable and liquid-impermeable resin sheet
The electrolyte solution is cut off by the amorphous alloy film 22.
3 does not come into contact with the non-aqueous electrolyte. And this
A seal formed with an exhaust port 15e provided with an air pressure adjusting chamber 20a.
The design capacity as shown in FIG.
A prismatic non-aqueous electrolyte secondary battery was prepared at mAh,
A water electrolyte secondary battery B was obtained. (2) Embodiment 2 As shown in FIG. 3, the exhaust unit 30 of the second embodiment
15 at the top and bottom of the exhaust port 15e provided in a part of
An upper mounting portion 15h and a lower mounting portion 15i are provided.
The same as the resin sheet 21 of the first embodiment is provided on the upper mounting portion 15h.
Fix the resin sheet 31 so as to shut off the outside of the battery
are doing. In addition, the lower mounting portion 15i has
Using an amorphous alloy film 33 similar to the fass alloy film 23
The periphery of the alloy film 33 is the same as the resin sheet 31 described above.
The composite film is fixed to the resin sheet 32 made of various materials.
I'm trying. Here, as in the first embodiment, the alloy film 33
The surroundings and the resin sheet 32 are bonded to each other by pressure bonding, heat welding, bonding, etc.
What is necessary is just to fix it using an appropriate means. Also on
Fixing between the part mounting part 15h and the resin sheet 31, and the lower part
The fixing between the mounting portion 15i and the composite film is also performed by pressure bonding, heat welding, and bonding.
What is necessary is just to fix it using suitable means, such as. This
Thereby, a composite film including the alloy film 33 and the resin sheet 32
A space is formed between the battery and the resin sheet 31 so that
Pressure adjusting chamber 30a for reducing the pressure difference between the unit and the outside of the battery
The formed exhaust unit 30 is configured. In this case, a part of the sealing body 15 is provided.
The upper and lower annular grooves as in the first embodiment are formed on the peripheral wall of the exhaust port 15e.
Since there is no need to form 15f and 15g, the exhaust port
Processing of 15e becomes easy. The upper part of the exhaust port 15e
And the upper and lower mounting portions 15h and 15i provided at the lower part,
Resin sheet 32 or a composite sheet composed of an alloy film 33 and a resin sheet 32.
If the composite film is fixed by appropriate means such as crimping, heat welding, bonding, etc.
As a result, these fixing steps are simple and easy. (3) Embodiment 3 As shown in FIG. 4, the exhaust unit 40 of the third embodiment
An exhaust port 15e is provided in a part of the exhaust port 15e.
An upper annular groove 15j and a lower annular groove 15k are provided on the peripheral wall.
Was. The upper annular groove 15j has gas permeability.
Resin sheet (eg, polyethylene (PE) sheet)
41 is fixed to cut off the outside of the battery. Ma
Further, the same amorphous content as the amorphous alloy film 23 of the first embodiment is used.
A plurality of fass alloy films 43 are prepared, and
The material around the film 43 is the same as that of the resin sheet 21 of the first embodiment.
To a resin film 42 to form a composite film. And this
Was fixed to the lower annular groove 15k. In this case, a plurality of amorphous alloy films 4
3, these amorphous alloy films 43 are used.
Increases in strength. This is because such an amorphous alloy
Since the gold film is generally produced by a quenching method,
Only thin films with a thickness of 30-50 μm and low strength can be manufactured.
To produce an amorphous alloy film with high strength
It is difficult. However, as in the third embodiment,
Is used by laminating a plurality of amorphous alloy films 43
This is preferable because the strength increases. 5. High temperature storage characteristics test Next, the high-temperature storage characteristics were examined. Where
The non-aqueous electrolyte secondary batteries A and B produced as described in
(Approximately 25 ° C.), at a charging current of 700 mA, the battery voltage
Constant current charging until it reaches 4.2V, and at a constant voltage of 4.2V
Constant voltage charging until the current value reaches 20 mA
Of the non-aqueous electrolyte secondary batteries A and B were fully charged. this
Thereafter, the non-aqueous electrolyte secondary batteries A and B were heated at 70 ° C.
It was placed in a warm bath and left for 3 hours. At this time, 1 o'clock
When the internal pressure of the battery is measured every time the time elapses, as shown in FIG.
Results were obtained. Also, every one hour, the non-aqueous electrolyte secondary
The thickness of the batteries A and B was measured, and the non-aqueous electrolyte
The ratio of the thickness of the secondary batteries A and B to the thickness is defined as the battery expansion rate (%).
As a result, the result as shown in FIG. 6 was obtained. Further
And fully charged non-aqueous electrolyte secondary batteries A and B at 70 ° C
It was placed in a heated thermostat and left for 10 days.
At this time, every 5 days, the non-aqueous electrolyte secondary battery A,
Measure the thickness of B and calculate the ratio to the battery thickness immediately after fabrication.
When obtained as a battery expansion coefficient, a result as shown in FIG. 7 is obtained.
Was done. From the results of FIG. 5, FIG. 6, and FIG.
As can be seen, the amorphous gas that selectively permeates hydrogen gas
Alloy film 23 (in this case, no experimental results are shown)
Is the exhaust part 30 using the amorphous alloy film 33.
The same applies to the exhaust part 40 using the amorphous alloy film 43.
Battery B provided with
Pressure rise and battery expansion coefficient are small.
Call This is either fully charged battery A or fully charged
Battery B is left (stored) in a high-temperature atmosphere (70 ° C.)
During storage, the nonaqueous electrolyte is decomposed and hydrogen gas is generated.
You. In this case, in the battery B, the air pressure adjusting chamber
Amorphous alloy that selectively permeates hydrogen gas into 20a
Since the gold film 23 is provided, the concentration of the generated hydrogen gas is
If it increases beyond a certain value, it will be discharged out of the battery.
As a result, if it becomes possible to suppress the rise in battery internal pressure,
In addition, the expansion coefficient of the battery can be suppressed. Against this
Thus, in the battery A, the amorphous alloy film 23 is provided.
Non-aqueous electrolyte is decomposed during storage
The generated hydrogen gas cannot be released outside the battery
As a result, the battery internal pressure increased and the battery expansion rate also increased.
It is thought. 6. Cycle characteristics test Then, the batteries A and B were separated by 700 m at room temperature (about 25 ° C.).
Constant current until the battery voltage reaches 4.2 V with the charging current of A
Charges, the current value reaches 20mA at a constant voltage of 4.2V
Charged to constant voltage until After this, a discharge current of 700 mA
It is said that the battery is discharged until the battery voltage reaches 2.75 V
The charge and discharge cycle is repeated 300 times,
The discharge capacity (mAh) after 300 cycles was determined. About
Thus, the initial discharge capacity and the discharge capacity after 300 cycles
The ratio was determined and determined as cycle characteristics. Then,
Assuming that the cycle characteristic of the pond A is 100, the cycle of the battery B
The characteristic is 120 and it is found that it has been improved by 20%.
Was. This is because in the battery A, the charge / discharge cycle
Hydrogen gas generated in the battery as the
The gas trapped between the electrode plates
Response capacity was reduced, and the discharge capacity was thought to have decreased.
Can be On the other hand, in the battery B, the hydrogen generated in the battery
The gas is an amorphous alloy that selectively permeates hydrogen gas
The charge / discharge cycle is required to be discharged out of the battery through the membrane 23.
Even if the gas progresses, the battery reaction is inhibited by the hydrogen gas.
And the discharge capacity was improved.
You. [0033] As described above, the non-aqueous electrolyte solution of the present invention
For secondary batteries, a sealing body that seals the opening of the outer can
Exhaust unit 20 for partially exhausting hydrogen gas generated in the battery
(30, 40), and the exhaust portion 20 (30, 40)
Permselective alloy membrane that selectively permeates hydrogen gas into the inside
23 (33, 43), the battery
The hydrogen gas generated inside the hydrogen selective permeable alloy film 23
(33, 43), it is discharged out of the battery.
You. As a result, even if the battery is left
Battery swelling can be suppressed. Also, hydrogen gas
Since the battery no longer accumulates in the battery,
Cycle performance is improved due to reduced reaction inhibition
The obtained non-aqueous electrolyte secondary battery can be obtained. In the embodiment described above, the book
Hydrogen permselective alloy selectively permeating hydrogen gas of the invention
An example of providing a membrane on a sealing body that seals the opening of an outer can
As described above, hydrogen selective permeation that selectively permeates hydrogen gas
Even if the transient alloy film is provided at an appropriate place on the outer can
Good. In the above-described embodiment, the water
Hydrogen selectively permeable alloy membrane that selectively permeates elemental gas
The alloy of zirconium (Zr) and nickel (Ni)
Amorphous alloy (for example, 36Zr-64Ni
Alloy) film, but in addition to this,
Palladium (Pd) or lanthanum-nickel (LaN
i) and the like may be used. Further, in the above-described embodiment,
Only for the case where the present invention is applied to a non-aqueous electrolyte secondary battery
Although described, the present invention is not limited to this, alkaline storage batteries,
Suitable for battery systems that generate hydrogen gas, such as lead-acid batteries.
It is clear that it can be used. Even in this case, water
Selectively permeable alloy membranes are installed at appropriate locations on the sealing body and outer can.
You should be able to open.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing a schematic configuration of a rectangular non-aqueous electrolyte secondary battery provided with a spiral electrode body, and FIG.
It is a figure which shows a cross section, and FIG.1 (b) is a figure which shows AA cross section. FIG. 2 is a cross-sectional view showing an exhaust unit of Example 1 in which an exhaust unit is provided in the sealing body of FIG. 1 and a hydrogen selectively permeable alloy film is disposed in the exhaust unit. FIG. 3 is a cross-sectional view illustrating an exhaust unit according to a second embodiment. FIG. 4 is a cross-sectional view illustrating an exhaust unit according to a third embodiment. FIG. 5 is a diagram showing a relationship between a standing time of a battery left at a high temperature and a battery internal pressure. FIG. 6 is a diagram illustrating a relationship between a battery storage time and a battery expansion coefficient when the battery is left at a high temperature. FIG. 7 is a diagram showing the relationship between the number of days of storage of a battery left at a high temperature and the coefficient of battery expansion. [Description of Signs] 10: non-aqueous electrolyte secondary battery, 11: negative electrode plate, 11a: negative electrode current collecting tab, 12: positive electrode plate, 13: separator, 14 ...
Outer can, 15: sealing body, 15a: negative electrode terminal, 15c: terminal plate, 15e: exhaust port, 15f, 15j: upper annular groove,
15g, 15k: lower annular groove, 15h: upper mounting part, 1
5i: Lower mounting portion, 16: Spacer, 20, 30, 40
... Exhaust part, 21, 31, 41 ... Resin sheet, 22, 3
2, 42: resin sheet, 23, 33, 43: amorphous alloy film

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Atsushi Obayashi             2-5-5 Keihanhondori, Moriguchi-shi, Osaka 3             Yo Electric Co., Ltd. F term (reference) 5H012 AA07 BB01 BB02 BB11 DD01                       DD06 DD07 DD11 EE01 EE04                       GG01 GG03 JJ02

Claims (1)

Claims: 1. A hermetic seal comprising: a positive electrode, a negative electrode, a separator for separating the positive electrode and the negative electrode, and an electrolytic solution in an outer can, wherein an opening of the outer can is sealed by a sealing body. Type battery, comprising: an exhaust unit for exhausting hydrogen gas generated in the battery at a part of the outer can or at a part of the sealing body; and hydrogen selective permeation for selectively transmitting hydrogen gas into the exhaust unit. A sealed battery comprising a conductive alloy film.